This paper presents a hierarchical design methodology based on the inversion factor (IF) as a key design parameter and the equations of the EKV MOS Model. A structured design approach is used to allow high flexibility. The efficiency of the methodology is demonstrated through the design of a fully differential folded-cascode OTA with gain boosting. Firstly, the partitioning into basic blocks is done. Then, each block is designed independently. The performance of the whole circuit is verified. © 2011 Tech Univ of Lodz.